1. Technical Field of the Invention
The present invention relates to an antenna equipment assembly and, in particular, to an operation and maintenance interface relating to the antenna equipment assembly.
2. Description of Related Art
In some antenna equipment assemblies, antenna near parts (ANPs), such as tower mounted amplifiers and active antennas with an array of power amplifier modules, are utilized with radio transmitter (TX) and receiver (RX) equipment. Some parameters (for example, gain) concerning operation of the antenna near parts may be configurable. The operation of the antenna near parts may further be controlled by software, and certain instances may arise wherein software upgrades need to be downloaded to the antenna near parts to correct bugs or provide for additional functionality. The antenna near parts may also have built-in test and supervision functions which need to be periodically executed. Still further, the radio transmitter and receiver equipment may need to have knowledge of the capabilities (such as gain, delay, and frequency characteristics) of the antenna near parts. In fact, in many instances, due primarily to the fact that these characteristics may change over time, the radio transmitter and receiver equipment may require real time (or near-real time) knowledge of the characteristics to avoid and appropriately respond to deterioration in system performance. The antenna near parts may further have the capability to detect faults. These faults in many cases need to be reported to the radio transmitter and receiver equipment. In this regard, it is further noted that the antenna near parts may further comprise several independent components, and thus the report may need to be originated from several sources.
With respect to functions performed for supervising transmitter antenna operation, one currently implemented method measures voltage standing wave ratio (VSWR) at the output of the transmitter equipment. This method is unreliable, and thus not preferred, when feeder loss between the transmitter equipment and the antenna is high, or when a tower mounted amplifier (or other auxiliary equipment) is utilized. In these cases, the VSWR measurements do not provide any accurate indication of the presence of a faulty antenna. Reliable supervision of transmitter antenna operation in these cases must be performed as close to the antenna as possible, and reported back to the transmitter and receiver equipment for analysis.
The antenna near parts are typically mounted near the physical antenna itself, and remote from the radio transmitter (TX) and receiver (RX) equipment. In order to facilitate parameter configuration, software downloading, execution of built-in test and supervision functions, real time (or near-real time) reporting of capabilities, reporting of detected faults from the potential several independent components of the antenna near parts, and supervision of transmitter antenna operation, a need has arisen for the establishment of an operation and maintenance communications link between the radio transmitter and receiver equipment and the antenna near parts.
One proposed prior art solution is to provide a separate cable connection between the radio transmitter and receiver equipment and the antenna near parts to carry operation and maintenance communications. Any included additional cables needed for operation and maintenance may be connected to the transmitter and receiver equipment via included external ports. This solution is not preferred, however, for a number of reasons. First, any cable used may become faulty (necessitating a replacement), or become disconnected, and lightning protection may be difficult to achieve. Second, where the antenna near parts comprises several independent components, a separate cable may need to be run from each component to the transmitter and receiver equipment, thus further magnifying the foregoing concerns of faults, disconnections and lightning protection. Lastly, if the transmitter and receiver equipment interface for operation and maintenance is provided through the external ports, there is a concern that the number of ports provided may be insufficient to handle the requisite number of operation and maintenance cables as well as handle other conventional alarm-related connections.
Another proposed solution is to communicate the operation and maintenance information over the existing radio frequency feeder connecting the transmitter and receiver equipment to the antenna near parts. This solution advantageously obviates the need to run multiple separate cables or occupy external alarm port connections. A commonly utilized method for communicating operation and maintenance information over the radio frequency feeder is through modulating a direct current applied to the feeder. Although providing a satisfactory solution, this method is limited in application because the applied signals communicating the operation and maintenance information may adversely affect the operation of some antenna near parts components, or interfere with the performance of certain supervision functions (such as tower mounted amplifier supervision) relating to the antenna near parts.
It is recognized, however, that signaling of operation and maintenance information over the radio frequency feeder is the preferred implementation. A need exists then for a system for more efficiently utilizing the radio frequency feeder to communicate operation and maintenance information. In particular, this need exists in the environment of a cellular telephone system radio base station.